Abstract:

The two main objectives of this thesis were to study if performance or long-term stability of dye solar cells increase as a result of electrolyte material purification. Not only the combined effect of the purification of all the electrolyte materials has been examined but also the effect of the purification of each compound has been compared. Furthermore, the specific reasons for cell degradation have been investigated where possible.

The overall degradation rate of the test solar cells during the aging test was faster than expected and thus the origin of this fast aging formed as the third main research question. Ultraviolet light was detected to be a very likely reason for the fast degradation and thus, additionally the effect of ultraviolet light on the cell aging has been discussed.

The secondary object of this study was to determine the proper procedures for performing long aging studies in the future. This task included the assessment of useful tests and the effects of unavoidably varying light intensity during the aging tests. Also statistical tests were introduced to the analysis of the results of the aging studies.

This study showed that the purification of electrolyte solvent does not affect the initial performance of the dye solar cells but increases the cell lifetime. The other electrolyte components were not detected to have any statistically significant effect on either cell lifetime or initial performance. The aging mechanism was discovered to be electrolyte bleaching, i.e. the consumption of charge carrying iodine in the electrolyte. The bleaching was clearly fastest in the cells that contained unpurified electrolyte solvent but the mechanism was present in all the cells. Additionally, the exposure to even relatively small amounts of ultraviolet light seemed to affect detrimentally cell lifetime through accelerated bleaching.Työn kahtena päätavoitteena oli selvittää, vaikuttaako väriaineaurinkokennon elektrolyytin materiaalien puhdistaminen myönteisesti väriaineaurinkokennon suorituskykyyn tai elinikään. Työssä ei tarkasteltu ainoastaan kaikkien elektrolyyttimateriaalien yhtäaikaisen puhdistamisen vaikutusta aurinkokennoihin, vaan eriteltiin myös yksittäisten elektrolyyttikomponenttien puhdistamisen vaikutukset. Lisäksi tutkittiin kennon ikääntymistä aiheuttavia tekijöitä.